The present invention relates to the analysis of haemostasis, clotting time, and platelet collagen interaction of non-anti-coagulated blood. Specifically, a disposable blood-handling device for making haemostasis measurements and thrombolysis measurements is described.
In the treatment of blood disorders, such as hemophilia, von Willebrand's Disease, and others, it is necessary to measure the clotting ability of human blood, and to assess the adequacy of the hemostatic function before an operation on patients having these disorders may be safely undertaken. In other disorders, such as myocardial infarction and stroke, thrombolysis or blood dissolution properties must be monitored and assessed repeatedly following recovery to prevent recurrence of a blood clot.
The haemostasis and thrombosis functions are related to the formation of platelets, red cell behavior and the condition of the vessel walls of a patient. In vitro techniques for measuring these properties have been slow in developing. One technique of in vitro analysis was described in a paper by Paul Didishen, at the Mayo Clinic, and reported in "Microscopically Typical Thrombi and Haemostatic Plug in Teflon Arteriovenus Shunts" in Dynamics of Thrombus Formation and Dissolution, S. A. Johnson, M. M. Guest, Eds., Lippincott, Philadelphia, USA, pages 64-71. This paper established the formation of haemostasis by passing a sample of anti-coagulated blood through a polyethylene tube which was punctured with a small hole to simulate bleeding. This effort demonstrated that haemostasis occurred at least in part from factors other than the vessel wall condition.
In building on this technique for in vitro establishment of haemostasis, European Patent Application No. 129425 describes a laboratory technique for measuring haemostasis. A polyethylene tube connected to a syringe of fresh blood is punctured with a small hole to simulate bleeding. The bleeding and clotting time of human blood samples in this arrangement can be repeatedly monitored and evaluated with and without the presence of various agents which promote haemostasis or thrombolytic activity.
In yet a further improvement of this technique, as described in International Patent Application No. PCT/GB87/00633, having an international filing date of Sept. 10, 1987, multiple channels of tubing are connected to individual syringes of freshly drawn blood. The multiple channels are simultaneously punched by a common punching needle. This permits the concurrent measurement of haemostasis and thrombolysis promoting agents on a single patient by providing two identical samples of blood, one of which may contain an agent promoting either haemostasis or thrombolysis, the other being native untreated blood.
These techniques remain impractical for operation by technicians employed in medical clinics. These clinics typically see many patients in a given day, and must have an in vitro diagnostic instrument which is easily operated and produces uniform, repeatable results. The measurements must be made quickly following drawing of a blood sample in order to obtain an accurate measurement of haemostasis. The equipment used to handle the blood samples should ideally be completely disposable to prevent the spread of disease carried by infected blood which is being tested. Additionally, it is desirable to avoid all contact with blood to prevent any disease being contracted by the laboratory personnel.